Executives from a rainforest charity that has been critical of the Leonardo DiCaprio Foundation’s reported ties to a Malaysian embezzlement scheme were reportedly denied entry to the London premiere of the actor’s climate change documentary on Saturday night.

According to the Hollywood Reporter, Bruno Manser Funds executive director Lukas Straumann and campaign manager Johanna Michel were barred from entering the London Film Festival premiere of Before the Flood on Saturday at the Odeon in Leicester Square.

The two were reportedly rebuffed by security guards, despite having tickets to the screening.

At a press conference in London on Friday, Straumann publicly called on the Oscar-winning Revenant star to return what his charity organization has termed “stolen money” to the Malaysian people, or else resign his position as the UN Messenger of Peace with a focus on climate change. The Bruno Manser Funds’ charity efforts center on rainforest preservation in the Southeast Asian country.

“If DiCaprio is unwilling to come clean, we ask him to step down as UN Messenger of Peace for climate change, because he simply lacks the credibility for such an important role,” executive director Straumann said at the event.

Earlier this summer, DiCaprio’s environmental-focused charity organization was the subject of a Hollywood Reporter exposé that claimed it received donations from funds misappropriated in the world’s largest embezzlement scheme.

According to a Justice Department complaint, $238 million improperly taken from Malaysian sovereign wealth fund 1MDB went to fund the production of DiCaprio’s 2013 film The Wolf of Wall Street, for which the actor won a Golden Globe in the starring role. The studio behind the film, Red Granite Pictures, was co-founded by Riza Aziz, the step-son of the Malaysian prime minister and now a central figure in international investigations concerning the 1MDB fund.

The exposé also alleged that figures connected to the embezzlement scheme donated artwork that was later auctioned off by the Leonardo DiCaprio Foundation at its glitzy annual gala in St. Tropez, France.

Since the exposé was released in August, pressure has mounted on DiCaprio to return what some have called the “ill-gotten” donations. The pressure comes as the actor has taken his National Geographic climate change documentary — in which he serves as narrator and tour guide — to film festivals around the world, including on the White House’s South Lawn for the inaugural SXSL festival earlier this month.